1. Field of the Invention
The present invention relates to a pattern forming method, and, a method of producing an electronic device and the electronic device, each using the same. More specifically, the present invention relates to a pattern forming process appropriate for a producing process of a semiconductor such as an integrated circuit (IC), a producing process of a circuit board such as a liquid crystal and a thermal head, and further a lithography process of photofabrication in addition to these, and, a method of producing an electronic device and the electronic device, each using the same. Particularly, the present invention relates to a pattern forming method appropriate for an exposure with an argon fluoride (ArF) exposure apparatus of which the light source is a far-ultraviolet light with a wavelength of 300 nm or less and an exposure with an ArF liquid immersion projection exposure apparatus, and, a method of producing an electronic device and the electronic device, each using the same.
2. Description of the Related Art
Currently, at the forefront of forming a pattern, ArF liquid immersion lithography has been used, however, a limit resolution of line:space=1:1, which is reachable by liquid immersion lithography using an NA 1.2 lens is approximately 43 nm.
In recent years, further improvement of the resolution has been required. As one of the newly proposed lithography technology, a double patterning process forming a resist pattern by carrying out two times or more patterning may be exemplified (for example, see Proceedings of SPIE, vol. 5256, p. 985 to 994 (2003) and Proceedings of SPIE, vol. 6153, p. 615301-1 to 615301-19 (2006)).
According to the double patterning process, for example, after patterning is carried out using a first resist composition to form a first resist pattern on a support, it is considered that a resist pattern with higher resolution than the resist pattern formed by one time patterning can be formed on the support on which the first resist pattern is formed by carrying out patterning using a second resist composition.
In the above-described double patterning process, the first resist pattern can be easily affected at the time of patterning using the second resist composition. For this reason, for example, there is a problem in that decrease in line width of the first resist pattern (thinning of the pattern) or film thickness reduction is occurred such that the shape thereof is damaged, therefore, a fine resist pattern with an excellent shape may not be formed.
In order not to damage the shape of the resist pattern, there is a technique of using, for example, a freezing material after the first resist pattern is formed, however, the technique is not preferable from the viewpoint of throughput improvement.
Accordingly, a resist in which a first resist or a second resist is designed for double patterning has been proposed (for example, see JP2009-282224A).
In a positive developing process combining an alkaline developer and a positive chemically amplified resist composition, which is a chemically amplified resist composition of which solubility in the alkaline developer increases by exposure, the exposed portion of a resist film is dissolved by the alkaline developer to be removed, and then a resist pattern is formed. When the positive developing process is compared to a negative developing process combining a negative chemically amplified resist composition and the alkaline developer, there are following advantages: (1) a structure of a photomask can be simplified, (2) a contrast sufficient enough to form an image can be easily obtained, and (3) properties of a pattern to be formed are excellent. For these reasons, there has been a tendency that the positive developing process is used for forming a fine resist pattern.
However, as devices are made finer, a trench pattern (isolated space pattern) or a hole pattern are hard to be formed than a line pattern.
When the trench pattern (isolated space pattern) or the hole pattern is formed using the positive developing process, the pattern is needed to be formed under the condition of weak intensity of incident light, so that the contrast of the intensity of light incident to the exposed portion and the unexposed portion is small, compared to the case in which the line pattern or a dot pattern is formed.
Therefore, the pattern forming ability such as resolution or the like is easily limited, a resist pattern with high resolution tends to be hardly formed. Here, a negative developing process (negative tone imaging process) combining the positive chemically amplified resist composition which is versatile and has priorities in various properties in order to form a trench pattern or the like with high resolution and a developer containing an organic solvent has been proposed (for example, see JP4554665B).
However, in regard to the negative tone imaging process, an optical image used in image formation is a negative image even though the positive chemically amplified resist composition is used as a resist, so that it is considered that the negative tone imaging process is not suitable for forming a line pattern or a dot pattern in which a positive image is favorable.